Distillation of crude petroleum



Sept. 4, 1928.

E. W. ISOM ET AL DISTILLATION OF CRUDE PETROLEUM Filed June 11, 1927 NS, E@

NS Ngmmwwk Patented sept. 4, 1928.

UNITED STATES PATENT oF'FlcE.

EDWARD W. ISOM, OF SCARSDALE, NEW YORK; AND EUGENE C. HERTHEL, F CHICAGO, ILLINOIS, ASSIGNORS TO SD'CLAIR REFINING COMPANY, OF NEW YORK, N. Y., A.

CORPORATION 0F MAINE.

DISTILLATION OF CRUDE PETROLEUM.

Application filed .Tune 11, 1927. Serial No. 198,250.

This inventionrelates to improvements in the production of gasoline from crude petroleum. The invention provides an improved method of distilling crude. petroleum whereby, in a single operation, its natural gasoline content is recovered together` with an additional amount of gasoline produced by mild cracking. l

In carrying out the present lnvention,

' lo crude petroleum including its natural gasoline content is subjected to distillation under relatively low super-atmospheric pressures and at relatively mild cracking temperatures. The natural gasoline content of the I5 crude petroleum is thus stripped or topped from the oil While at the same time an additional amount Vof gasoline formed by the mild cracking conditions to which the oil is subjected is recovered together With the natzo ural gasoline content. To provide for uniform heating and to avoid local overheating, the oil is heated by repeated circulation at relatively high velocity through heatlng tubes from and to a large body maintained in a vaporizing zone from which the gasoline vapors are taken ofi'. A bed of finely divided absorbent or filtering material is maintained Within the body of oil in the vaporizing zone and extending entirely across it in the path of the oil circulating and recirculating through the heating tubes so that the circulating oil" is repeatedly passed through this hed of finely divided material as it is repeatedly passed through the heating tubes. To reduce any interference with free circulation of the heavy oil circulating in the still to a minimum, this bed of finely divided absorbent or filtering material is made relatively thin. Crude petroleum is supplied to the circulating body of oil and the heavy oil remaining after separation of gasoline, including the natural gasoline content and that formed by cracking, is discharged continuously during the operation. The stripped or topped oil discharged Jfrom the still is Withdrawn from beneath the bed of linely divided filtering or absorbent material, that is from the oil circulating to the heating tubes before it enters the heating tubes and after passage through the bed of finely divided material.

The vapors including the gasolinel vapors separated in the vaporizing zone may be subjected to a refluxing operation for separation and return to t-he circulating body of oil in the still of heavier components. In one particularly advantageous method of operation, the vapors taken oitn from the vaporizing zone are subjected to a reluxing operation into which the crude petroleum is direcly introduced. In this method of operation,

the crude petroleum is employed to cool and reflux the vapors and at the same time is preheated thereby. The lighter components of the crude petroleum including its natural gasoline content may thus be largely vaporized in the refluxing operation to escape therefrom with the gasoline vapors entering the reiluxing operation from the still. To the extent that the natural gasoline content of the crude petroleum is thus separated in the retluxing operation, the heat supplied to the circulating body of oil in the still is more eti'ectively used for cracking and likewise any possible tendency to overcracking of the natural gasoline content of the crude petroleum is eliminated. In this same respect, it is also advantageous to return reflux condensate from the refluxing operation to the body of oil in the Vaporizing zone above the bed of finely divided filtering or absorbent material to promote complete separation of light components from the reflux condensate and from any admixed unvaporized crude oil. By operating in this manner, circulation of such separated light components through the heating tubes is avoided, eliminating any tendency to overcracking of such components and also providing for more eilective use in the conventional manner, in elevation and partly -in section and with parts broken away, one

ranged, a firebox 8 connected to one end of this heating flue and a stack flue 9 connected to the other end. Part of the escaping waste heating gases may be returned and recirculated through the heating flue in admixture with fresh hot products of combustion from the firebox b y means of return flue 1() which is provided with suitable forcing means. Arranged in the bulk supply drum, below the normal liquid level therein, and between the outlet to the circulating connections 4 and the inlet from the circulating connections 6, is a bed 11 of finely divided material extending entirely across the bulk supply drum. This bed is carried by suitable` supporting means adapted to retain the finely divided absorbent or ltering material and to permit free passage of oil. It may be made up, for example, of one or more screens of graduated fineness arranged b'etween perforated plates or gratings. Vapors from t-he bulk supply drum 1 escape through connection 13 to the lower end of the reflux tower 14, pass upwardly therethrough, and vapors remaining uncondensed escape therefrom through connection 15 to condenser 16 arranged to discharge into receiver 17. The receiver 17 is provided with an outlet 18 for the distillate product and an out-let 19 for uncondensed vapors and v gases. Pressure in the system maybe maintained by means of valve 20, or by suitable y valves arranged beyond the condenser or receiver. Connection 21 is provided for the supply of crude petroleum to the upper end of the refiuxtower 14. Refiuxcondensate and any admixed unvaporized crude oil flow from the lower end of the reflux tower. through cnnection 22, either to the body of 011 in the bulk supply drum above the bed 1 1 through connection 23 or to the body of 011 in the bulk supply drum beneath the bed 11 through connection 24. Connections 23 and 24 are provided with suitable regulating valves, as illustrated, to permit direction and distribution of the oil iiowing from the lower end of the redux tower through connection 22 as desired. Connection 25 is provided for the discharge of residual oil fromV the still during operation; it will be noted that this connection opens into" the body ofoil in the bulk supply drum beneath thebedqll.

Cool oil, for example part of the crude oil subjected to distillation, is supplied through connection 26 for cooling and lubricating the bearings of thecirculating pump 7. An amount of crude oil in excess of thatrequired for cooling and lubricating the pump bearings may also be introduced through this connection; for example where the amount of oil supplied to the operation exceeds that necessary to effect the desired refluxing in the tower 14. Connection 27 is provided for pumping out the still at the end of a run and for initially charging it at the beginning of a run.

In carrying out the invention in the apparatus illustrated, a bed of nely divided absorbent or ltering material, such as full ers earth, or similar absorbent earths or clays, pulverized coke or calcined bauxite, is

arranged on the support means 12 in the' bulk supply drum 1. Fullers earth isv a particularly.advantageous material for this purpose. This bed 0f finely divided material may consist, for example, of -30 mesh fullers earth and may be about 4 to 6 inches in depth.' The still is then charged with oil and brought to operating conditions of temperature and pressure. This initial charge may be of the crude oil to be subjected to distillation, or, particularly if the period required to bring the still to operating conditions of temperatureand pressure is somewhat prolon ed, it may be of gas oil character stock. he still is' advantageously operated under pressures in the neighborhood of to 60 pounds per square inch andV the circulating body of oil maintained at a corresponding temperature; this temperature will vary with different crude petroleums, but for the pur ose of illustration it may run in the neigh orhood of 650o to 725 F.

fter the still is brought to operating conditions of temperature and pressure, the introduction of crude petroleum through connection 21 is begun, and the supply of crude petroleum through this connection is regulated to condense and reflux in the tower lll those components of the vapors entering the lsluggish circulation Q through the heating tubes is noted" in operation; more or less of this oil mixture may be'supplied through connection 24,t ov the'body of oil in the bulk supply drumbeneath thebed of filtering or absorbent material. The distillate product, including the natural gasoline content of the crude petroleum and that produced by the mild cracking conditions prevailing in the still, is discharged through connection 18..

The present invention makes it possible to separate the natural gasoline content from crude petroleum together with an addltlonal amount of gasoline produced by cracklng and at the same time to obtain a residual topped or stripped crude oil which is readily susceptible to further treatment in the usual Way, that is the Way in which topped or stripped crude oils are usually treated. No serious difliculti'es are encountered in such further treatment, and particularly diiiiculties due to any suspended solid material formed in the combined cracking and topping operation are avoided. e claim: l. An improved method of producing gasoline from crude petroleum, which comprises maintaining a body of oil ina vaporizing zone and maintaining a bed of finely divided absorbent or filtering material Within `said body and extending entirely across it, circulating oil from said bod-y from beneath said bed of finely divided material through heating tubes and backto the body of oil above said bed of finely divided material and heating it to a mild cracking temperature therein, supplying crude petroleum to the circulating body of oil, taking oif vapors.

1 including vapors of the gasoline product from said residual oil from the body of oil lfrom beneath said bed of nely divided material.

2. An improved method of producing gasoline from crude petroleum, which comprises maintaining a body of oil in aKvaporizin zone and maintaining a bed of 'ely divide absorbent or filtering material ywithin, said -body and extending entirely across it, circulating oil from said body'from beneath vaporizing zone, and taking offk said bed lof nely divided material through heating tubes and back4 to the body of oil above said bed of'finely divided material and line product from said refluxing operation,

introducing crude petroleum into the vapors in said refluxing operation, returning reflux condensate from said reiuxing operation to the circulating body of oil together with admixed unvaporized portions of the crude petroleum supplied to the refiuxing operation, and taking off residual oil from the body ofl oil from beneath said bed of finely divided material.

3. An improved method of -producing gasoline from crude petroleum, which comprises maintaining a body of oil in a vaporizing zone and maintaining a bed of finely divided absorbent or filtering material within said body and extending entirely across it, circulating oil from said body from beneath said bed of finely divided material through heating tubes and back to the body of oil above said bed of finely divided material and heating it to a mild crackingtemperature therein, supplyingcrude petroleum to the circulating body of oil, passing vapors from said vaporizing zone through a refiuxng operationand taking oil' vapors including vapors of the gasoline product'from ,said refluxing operation, returning reflux condensate from said ref iuxing operation tothe body of oil above said bed of finely divided material, and taking 0H residual oil from the body of oilfrom beneath said bed of finely divided material.l e f In testimony whereof weaiiix our signatures.

. EDWARD W. IsoM,

y EUGENE c. HEETHEL.

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